1. Field of the Invention
The invention relates to a power control device, and more particularly to an optical power stabilizing device.
2. Description of the Related Art
FIG. 1 shows a conventional optical power control device adapted to receive a direct-current input voltage Vin and generate a working current I to drive a laser diode 11. When the input voltage Vin is constant, the working current I has a constant magnitude.
However, the working current I resulting from the direct-current input voltage Vin will increase temperature of the laser diode 11, and characteristics of the laser diode 11 may thus vary.
Referring to FIGS. 1, 2 and 3, the laser diode 11 has a forward voltage varying with ambient temperature. When the laser diode 11 is driven with a constant current, rise in the ambient temperature may result in drop of the forward voltage (see FIG. 2), so that optical power of the laser diode 11, which is proportional to a product of the forward voltage and the working current, drops with rise in the ambient temperature, as best shown in FIG. 3.